1. Technical Field
The invention relates to electronic test and measurement equipment. In particular, the present invention relates to calibration of electronic test and measurement equipment such as vector network analyzers.
2. Description of Related Art
A vector network analyzer (VNA) measures a performance of a radio frequency (RF) and/or microwave/millimeter wave device under test (DUT) and produces measured results in terms of network scattering parameters. As with all test and measurement equipment, VNAs introduce errors into measured S-parameter data produced for a given DUT. The presence of these errors distorts or corrupts the measurements of actual S-parameter data for the DUT.
Fortunately, the effects of at least the so-called ‘systematic’ errors introduced by the VNA and any associated test system (e.g., cables, connectors, fixture, etc) may be characterized and subsequently removed from measurements of the DUT through VNA calibration. Unfortunately, it is not always convenient or even possible, in many cases, to construct and/or characterize a set of calibration standards, the defining parameters of which are known with sufficient accuracy for calibration purposes over a frequency range of interest. Moreover, even in cases where it is possible to manufacture precision standards, the calibration standards may be very expensive owing to a need to control and accurately characterize the performance of such standards.
Accordingly, it would be advantageous to calibrate a VNA without relying on using a set of calibration standards having accurately known characteristics. Such a calibration would solve a long-standing need in the area of calibrating a VNA using calibration standards.